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New Regulations for n-Propyl Bromide (nPB) Solvents


Reliance Specialty Products wants to let you know about regulatory changes that are happening with n-Propyl Bromide and how we can help if you decide you want to switch-out of nPB or improve your cleaning equipment.

Key Points:

  1. nPB is now REGULATED under NESHAP and is considered a Hazardous Air Pollutant (HAP)
  2. There are now Air Permitting and State Reporting Impacts
  3. There will be Shipping Classification Impacts
  4. There will be Waste Disposal Impacts
  5. You can continue to use nPB. There is no immediate need to move out of nPB, but you may need to change permitting.

How Reliance Can Help:

  1. We can help you switch into AeroTron™-100, a safer solvent, as we have done for many of our current nPB customers. We can provide a sample and test clean parts in AeroTron™-100.
  2. Next, Reliance can also help you with assessing your current vapor degreaser and recommending upgrades or modifications.
Request solvent sample
Request test part cleaning

nPB is now considered a HAP under NESHAP.

AeroTron™-100 is a direct nPB replacement that does not require permits or reporting.

nPB is REGULATED under NESHAP, the National Emission Standards for Hazardous Air Pollutants by the US EPA and is now considered a Hazardous Air Pollutant (HAP).

Unexpectedly, on January 5th, 2022, n Propyl Bromide became a HAP (Hazardous Air Pollutant) regulated under NESHAP. The specifics of how it will be regulated under NESHAP will be provided by the US EPA at some time in the future.

As a side note:
No solvents have otherwise been added to NESHAP since it was originally enacted in the late 1990's - so no one knows what the requirements will be or what the timeframe for issuance is. However, we anticipate that the use requirements will be similar to TCE, PERC and Methylene Chloride that were part of that early regulation.

Implications of NESHAP Regulation of nPB

First, there are Air Permitting and State Reporting Impacts

nPB was formerly only a VOC (Volatile Organic Compound), but not a HAP under NESHAP. Therefore, the type of operating permit you currently have is likely a simple air-operating permit for VOC emission. If you decide to stay with n Propyl Bromide, you will need to switch-over to a HAP operating permit.

Permits are issued by each state and each state's permitting rules vary. For a HAP, there are typically small emitter permits and large emitter permits known as Title 5 permits.

The HAP permits typically are more expensive and require periodic reporting to establish compliance with the HAP requirements and report the amount of HAP's emitted. HAP permits also require more comprehensive vapor degreaser containment features and operating procedures. As mentioned earlier, specific requirements under the NESHAP regulations for nPB are not yet issued.

Also, each state's DEQ, Department of Environmental Quality, will need to address the re-permitting and final reporting requirements for nPB now that it is a HAP.

The second implication of NESHAP is Shipping Classification Impacts

nPB is currently not regulated for shipment. However, it is likely to be classified by the DOT as hazardous for shipment at some point and treated in the same manner as TCE, MC & PERC. Our understanding is that this will occur as a separate action by the DOT (Department of Transportation).

The third implication of NESHAP classification is Waste Disposal Impacts

Currently, nPB is not a RCRA hazardous waste for disposal. RCRA is the Federal Resource Conservation and Recovery Act. However, we anticipate in a similar manner to the other NESHAP solvents, n Propyl Bromide will likely be classified as a RCRA hazardous waste for disposal.


You can continue use nPB. Companies have been using TCE, PERC and MC under NESHAP for 25 years. And NESHAP in and of itself does not preclude continued use, it is just more involved.

Immediately, the main issue with nPB is your state air permitting (as discussed earlier). Since each state handles its own air VOC, HAP permitting, you will need to check with your state for their immediate requirements for re-permitting of nPB.


The regulation of nPB, TCE, PERC and MC is underway under TSCA 6A, the Toxic Substances Control Act. This regulation gives the US EPA broad authority to regulate - and is capable of resulting in a phase-out or ban of n propyl bromide or any of the other solvents they are considering. A ban, if it occurs, would likely have a phase-out period.

TCE a couple of years ago was proposed banned for vapor degreasing. The USEPA Proposal was 18 months for phase out of manufacturing and a 36 month phase out for use. Thus, there was a 3-year period. The earlier proposal for TCE was withdrawn and is now again going through the process under TSCA 6 A along with nPB, PERC and MC.

Proposed regulations under TSCA 6A for nPB, TCE, PERC and Methylene Chloride are expected to be issued this year 2022.


There is no immediate need to move out of nPB, but you may need to change permitting immediately or when your State otherwise requires it. You will need to comply with the HAP permit reporting. The TSCA 6A is still in process and what the regulation of nPB will be under that regulation or if a phase out is part of it is unknown.

Here is how Reliance Can Help:

First, we can help you switch into AeroTron™-100, a safer solvent, as we have done for many of our current nPB customers. AeroTron™-100 is the next generation solvent that is a direct, drop-in replacement for nPB.

Next, Reliance can also help you with assessing your current vapor degreaser and recommending upgrades or modifications.

Please give us a call at 847.640.8923 or Contact Us for additional information.

We can test clean sample parts for you in AeroTron™-100 or

We can provide you with a sample of the AeroTron™-100 or

We are available for a technical consultation to help you navigate options.

Reliance takes a comprehensive approach to helping you assess your situation and your options.
We look forward to working with you.

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AeroTron™-100 Means Improved Health & Safety Profile - 150 PPM

Excellent Health, Safety & Regulatory Profile As Compared to nPB

AeroTron™-100 Benefits are Significant:

Regulatory AeroTron™-100 nPB
NESHAP Reporting Not Required Required
Hazardous Air Pollutant (HAP) Reporting None - Not Required Required
IARC Cancer Classification None - Not Listed Suspected
Manufacturer's Workplace Exposure Guidelines 150 ppm - 8 hour TWA 10 ppm - 8 hour TWA
RCRA NON-Hazardous Waste NON-Hazardous Waste
Department of Transportation (DOT) NOT Regulated NOT Regulated
Title V Permit NOT Required NOT Required
OSHA HAZCOM Record Keeping/Reporting NOT Required Hazard Warning Required
Prop 65, CA Yes Yes
Clean Water Act NOT Regulated NOT Regulated
VOC Yes, but variable Yes, 100%
US-EPA SNAP Approved Yes Yes
AeroTron™-100 vapor degreasing solvent performance

Excellent for Vapor & Ultrasonic Cleaning

AeroTron™-100 Plastic Compatability Testing

Plastic AeroTron™-100 Resistance Plastic AeroTron™-100 Resistance
POM Excellent HDPE Excellent
ABS Poor PEI Excellent
CPVC Fair PPO Poor
ETFE Excellent PP Fair
NYL Excellent PS Poor
PBT Excellent PSU Poor
PEEK Excellent PVC Poor
PVDF Excellent PU Fair
PC Fair PTFE Excellent
AeroTron<sup>®</sup>-100 vapor degreasing solvent performance

AeroTron™-100 Metal Compatability Testing

METHODS MIL.T-81533A 4.4.9 and TMO193-2000

Metal AeroTron™-100 Compatible Metal AeroTron™-100 Compatible
Aluminum 1050 Yes Mild Steel Yes
Al-Bronze 614 Yes Carbon Steel Yes
Copper Yes Stainless 303 Yes
Naval Brass 464 Yes Stainless 316 Yes
Tin-Bronze 903 Yes Stainless 330 Yes
Tin Yes Tungsten-Carbide Yes
Hastalloy-B Yes 5 Sn/95 Pb Yes
Inconel 600 Yes 70 Sn/30 Pb Yes
Nickel Yes Titanium 5-2.5 Yes
Zinc Yes Silver Solder B AG8 Yes
Lead Yes Silver Yes
Magnesium Yes Gold Yes

Typical Applications by Industry


Use AeroTron™-100 vapor degreasing solvent as an nPB alternative for the removal of greases, oils, silicone, masking waxes, masking lacquers, NDT dye penetrants, drawing lubricants, coolant residues and adhesives. Also ultrasonic vapor degreasing for removal of metal fines, polishing abrasives and blasting media.


AeroTron™-100 easily removes flux and flux residues, polar and non-polar contamination, and cleans electrical assemblies and fingerprints as effectively as nPB.


Cleaning of potting and masking waxes and fingerprints.

Metal Fabrication & Coating

Cleaning prior to coating, welding, brazing, or adhesive bonding.
Use AeroTron™-100 to replace n propyl bromide for vapor degreasing, ultrasonic cleaning and cold wipe cleaning processes to achieve near residue free surface cleanliness prior to plating, painting, physical vapor deposition (PVD) or robotic welding, vacuum brazing, or adhesive bonding of metal parts.

Getting Started with AeroTron™-100 Is Easy!

With these Performance Validation Options:

Request sample part cleaning
Complimentary test cleaning of your sample parts in our lab. We return your parts with a report and reference videos.
Request tech consultation
A comprehensive technical discussion with your team to provide the information you need to make productive decisions.
Request solvent sample
Request a complimentary sample of AeroTron™-100 for testing at your facility.

Easy Change Over to AeroTron™-100

Performance Properties AeroTron™-100 nPB
Boiling Point 116° F / 47° C 160° F / 71° C
Flash Point, by ASTM D93-TCC None None
Evaporation Rate Quickly & Completely Quickly
Azeotropic Composition Yes Yes
Broad Metal Compatibility Yes Yes
Hydrolysis Highly Stable Not stable-requires stabilizers
Distillable Yes Yes
Kauri Butanol Value 93 130
Non-Volatile Residue < 10 ppm < 10 ppm
Odor Very Mild Strong

No special ASTM procedures are needed to use AeroTron™-100 as a replacement for nPB.


  1. DRAIN: the vapor degreaser sumps (using solvent transfer pump), spray reserve tank, water separator and filtration tank of old solvent.
  2. SET: the temperature control settings for 116 F (47 C)
  3. FILL: the boil sump and immersion sump with AeroTron™-100

Use AeroTron™-100 As An Alternative to nPB for Asphalt Extraction

AeroTron™-100 can be used as effectively as nPB in asphalt extraction.

Because AeroTron™-100 is non-flammable, it is suitable for use in any asphalt extraction process. It is very fast acting and removes the bitumen / tar easily from samples. AeroTron™-100 can be used as a direct nPB replacement in asphalt extractions.

Excellent Technical Support for Seamless Transition

ULTRA™ vapor degreasers

Reliance Specialty Products is the world-class leading manufacturer of both vapor degreasing equipment and vapor degreasing solvents. At Reliance, we take a comprehensive, systemic approach to solvent parts cleaning. Our vapor degreasing equipment manufacturing expertise combined with our years of working with a variety of solvent cleaning options make us able to support our customers in a variety of practical ways. We are here to help you easily switch over to AeroTron™-100 and support your transition into an effective solvent that is better for your company, your people and the environment.

vapor degreasing turn-key systems
Reliance Specialty Products
Reliance Specialty
Products, Inc.
154 Easy Street
Carol Stream, IL 60188

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